Telephone system.



W. AlTKEN.

TELEPHONE SYSTEM. APPLICATION mm AUG. 12, 1911.

2 SHEETS-SHEET l- 7 Z [12V922f0f' 5 5% M71101?) Aizkezz THE NORRIS PETERS 60., PHQTO-LITHQ, WASHINGTON. Dv c.

- W. AITKEN, TELEPHONE SYSTEM. APPLICATION FILED AUGJZ. I911.

Patented June 22, 1915.

2 SHEETSSHEET 2.

THE NORRIS PETERS ca, PHOT0 LITHCL, WASHINGTON, D. c

WILLIAM AI'IKEN, OF LIVERPOOL, ENGLAND.

TELEPHONE SYSTEM.-

Specification of Letters Patent.

Patented June 22, 1915.

Application filed August 12, 1911. Serial No. 643,674.

To all whom it may concern Be it known that I, l/VILLIAM AITKEN, a subject of the King of England, and a resident of Liverpool, England, have invented a new and useful Improvement in Telephone Systems, of which the following is aspeci fication.

My invention pertains to telephone switching systems and relates especially to novel and improved methods of switching particularly applicable in small isolated eX- changes or branch exchanges. In my application for United States Letters Patent, Serial No. 588,645, filed October 2%, 1910, I described a telephone system particularly adaptable to private branch exchanges wherein especially designed switching mechanisms were em loved for establishing connections between the trunk lines and the various local lines, these switching mechanisms being provided with electromagnetic disconnecting means automatically operated. In my present application I provide an improved-form of such switching mechanisms, and adapt it, not only to use on trunk lines, but to use on all lines whether local or trunk. I provide electromagnetic, automatically operated disconnecting means for these switches.

i It is the object of my invention to dispense entirely with plugs, jacks and cords,

and to provide for the connection of the lines by means of the special manually operated switches, which act automatically to disconnect the lines at the proper time with out the attention of the operator.

In order to disclose the application of the a paratus, circuits and principles involved in my invention, 1 illustrate it in the accompanying drawings.

Referring to these drawings, which form a part of this specilica tionlligure 1 shows a front elevation of my improved switching mechanism; Fig. 2 shows a rear elevation of the above; Fig. 3 shows an elevation partly in section, the section being taken on the broken line- AA of Figs. 1 and 2', Fig. l is a sectional view taken on the broken line P-B of Fig. 3; Fig. 5 shows an elevation partly in section of a modification of my improved switching mechanism; Fig. 6 shows in diagram complete apparatus and circuit arrangements of my invention.

Referring especially to Figs. 1, 2, 3 and t,

in which like numerals indicate correspond.

ing parts throughout, 1 show different views of what I will call a multiple contact electromagnetic switch, by which, in connection with certain circuit arrangements hereinafter described, I am able to maintain cir-' cult connections by electromagnetic means during conversation and to attain automatic disconnection by such connections at the cessation of conversation. The switch consists in general of an eloctromagnet having a manually operated armature and under control of a telephone line; selective groups of springs arranged to perform the switchmg functions necessary in connecting lines for conversation, and means for manually operating the armature of the electromagnet to perform the desired switching. The armature is normally held from engagement with the spring groups by means of a spring which is compressed when the switch is manually operated, and which serves to auton atically restore the armature and also the springs utilized in switching when the said electromagnet ceases to be energized. The switch also performs certain other functions which may be placed under its control, due to the relative sequence of operation between such function and the operation of the switch.

In the figures just referred to, 31 is an electromagnetic coil with a core 31 and provided with a cup 32 of magnetic material. This cup 32 and its contained electromagnetic coil 31 and core 31 are supported on a mounting plate 33 by means of brackets 34, 34, 34: 34: Placed on the outside surface of cup 82, and supported by it, are the selective groups of springs 5 12 13 etc. The number of these groups of springs may be increased as the demand necessitates, being limited only by the width of the springs and the diameter of the cup 32 on which they are supported. It the on change, with which it is desired to use this switch, is of such size as to require more sets of springs, then they may readily be mounted as described, the capacity may be increased by means of a shallow cup of greater diameter than the electromagnetic cup and fastened to its rear end, thereby increasing the diameter on which the springs may be mounted, and consequently the available space for mountingsuch springs. The circular disk armature 38 and the circular disk 39 are mounted at the end of, shaft 40 and securely fastened thereto. On the disk 39 is placed an insulating knob or 'ular group of springs 5 plunger 39 so positioned with respect to the groups of springs 5 12 13 etc., as to be able to engage any particular group when set in proper rotary position. The disk 39 and the plunger 39 attached thereto, may

ture 38, when'moved to a position adjacent to the electromagnet, will be attracted by it,

pointer or finger 43.

as long as it is energized. In order to restore the shaft and its associated members to normal when the electromagnet ceases to attract the armature 38, the shaft 40 is provided with a restoring spring 48, which is compressed when the armature 38 is moved to a position adjacent to the poles of the electroinagnet, one end of the spring bearing against a surface of and the other against a surface of 46.

In order to aid the operator or attendant in properly setting the switch, the mounting plate 33 bears on its external surface index marks, shown at 42, 42 42 etc. The shaft 40 also has securely fastened to it the Therefore, with the apparatus so assembled that finger 43 is directly above the plunger 39 and the index marks 42, 42 42 etc., so placed on the mounting plate 33 as to be directly above the groups of springs 5 12 13 etc., the operator is assured that, with the index finger pointed to the identification mark of any particular group of springs, when the knob 41 is depressed, the plunger 39 will be brought into proper engagement with that group of springs. In order to prevent the depression of the handle 41 at any position other than that in which the plunger 39 is positioned directly over a group of springs, a slotted cylindrical tube 44 is provided and securely fastened to the mounting plate 33. Rigidly secured to the shaft 40 is an inverted cup-shaped piece 45, hearing projections at two diametrically opposite L points, so formed as to readily slide into the slots of 44 when placed in the proper position. These slots are so positioned with respect to the groups of springs, and the projecting portions of 45 with respect to the finger 43, as only to allow of the depression of the shaft 40and its associated parts when said shaft is properly set with respect to a particular group of springs. To further assist the operator in determining when the shaft 40 and its associated parts are in the proper position for depression, it is provided with an additional means of determining. its rotary position. This additional means consists of a cross-piece 46, associated with the shaft 40 by means of a pin riding in a slot through said shaft, and having spring actuated projecting members 47 and 47 riding on the internal cylindrical surface of 44, which successively engage the slots as handle 41 is rotated. By this means the operator may readily determine, by the variable friction encountered when rotating the handle, the particular places at which it is proper to depressit. The method employed in associating these parts insures that the member 46 and the shaft 40 shall always bear the same relative rotary position, regardless of the longitudinal position of the shaft.

The key 49 and the drop or signal 23, mounted above the switch proper just described, are the listening and holding key and the line signal, respectively. The key 49 is mounted on the plate 33 and has rigidly attached to its rear end the finger 49 ,which, when the key is moved to operate the lower springs of the group 2 moves to a position adjacent to disk 39. Therefore, when the key is so set and when the handle 41 is depressed, the disk 39 will engage the finger 49 and restore the key 49 to its normal position. Resting against the upper long spring of group 2 is an extending finger which serves to restore the shutter 22 of drop 23 when the handle of key 49 is moved downward.

In Fig. 5 is shown a modification which employs the same general arrangement of switching device as shown in Figs. 1, 2, 3 and 4, but which has the additional features, such as providing for the operation of a common group of springs whenever the switch is operated, and also of providing for the restoration of the line signal when the switch is operated before a particular selective group of springs. In this figure the corresponding parts have the same numerals as in the preceding figures. The common group of springs is operated as follows: The disk 39 engages at its circumference with the forked end of lever 24, and these parts are so related to each other that when the switch is operated the end of the lever 94 opposite to that which engages with the disk 39 will move to the right and thereby actuate the springs of group 2 The group 2 will, therefore, be actuated whenever the handle 41 is operated, regardless of the particular group of springs 5 12 .3 etc, before which the plunger 39 has been placed.

Mounted on the plate 33, and directly above the multiple contact switch, is a drop or line signal 26. Provision is made for restoring the shutter 27 of this drop after being actuated. Between the upper long spring of the group of springs 18 and finger 28 is placed a piece of insulating material, which will impart to the finger 28 an upward movement when the plunger 39 is inserted to actuate the springs of this group. The member 28, when moved upward, Will return the shutter to its normal position.

In Figs. 1 to 5, inclusive, I have shown, for convenience of illustration, a certain arrangement or the auxiliary devices operated by the switch proper. However, I do not wish to limit the arrangement to that shown herein, as it is obvious that variations may be employed without departing from the spirit of my invention; as, for example, the group of common springs 2 shown in Fig. 5, may be mounted in a similar position with respect to the switch of Fig. 3, and in fact, I find it desirable to do this.

I will now disclose the method of operation and the circuit arrangement in connection with the switching mechanism, whereby the desired operations are accomplished.

Referring to Fig. 6, which shows in diagram the complete apparatus and circuit arrangement of my invention as applied to a branch exchange of the common battery type, T have shown three local lines connected thereto and one trunk line extending 'to the central or public exchange. In order to render the circuits as simple as possible and at the same time to show the arrangement of the mechanical parts of the switches as clearly as is consistent with the simple circuit arrangement, I have arranged the individual selective groups. of springs radially about a dotted circle which might be assumed to represent the cup portion upon which they are mounted in practice, and within this circle I have placed the common group of springs and the electromagnet. In other words, those parts within the dotted circle are the ones brought into action whenever the switch is operated, and the parts outside and adjacent to the dotted circle, consisting of spring groups, are the ones actuated dependently upon the particular position in which the switch is set before being operated. The springs of the selective and common groups are shown as they would appear if a transverse section were passed through them at the contact points. The terminals for the local lines are shown 5, 6 and 7, and for the trunk line at 8. Switch 1 is associated with the trunk line 8 and switches 2, 3 and t are associated with local lines connected to the terminals 5, 6 and 7, respectively. With the trunk line 8 is associated a linesignal '18, a listening and holding key 17, and a holding coil. The trunk line apparatus is of the general type, as shown in Fig. 3. The ringing keys 1 1, 15 and 16 and signals 9, 10 and 11 are types well known in the art and are associated with the local lines, 5, 6 and 7, respectively,

in an obvious manner. A selective group of contacts 5 5 and 5*, one on each of the switches 2, 3 and 4, respectively, is employed for connecting the operators telephone set to the local line associated with each switch and may be termed the listening group.

The selective groups of contacts 12 12 12", and 13 13 and 13' are employed in establishing connections between two of the local stations or between one of the local stations and the trunk line. The coils 31, 31 and 31*, associated with the switches 2, 3, and l, respectively, are for holding the respective switches in an actuated position during conversation, and also serve as batc tery feed coils for the local station transmitters when two local stations are connected. The relays 1 1 and 1*, associated with the switches 2, 3 and l, respectively, are of the make before break type and are for the purpose of providing means for holding the switches 2, 3 or 4 in an actuated position when station 5, 6 or 7 is connected for co versation with the trunk line 8, it being understood that underthese conditions the battery current for energizing the transmitter of the local subscriber is supplied over the trunk line instead of being supplied locally as in the case when two local stations are connected for conversation. The switch 1 is associated with the trunk 8 and has the selective groups of contacts 12 and 13, which are for the purpose of establishing connection between the trunk line and a line 017' a local station. The coil 31 is for the purpose of retaining the switch 1 in an operated position, and its circuit is controlled directly by the contacts of the slowacting relay 1 the winding of which'is in bridge with a non-inductive resistance in order to impair the speech currents as little as possible.

The relay 1 is of a type well known in the art, in which the operation is retarded when deenergized by a mass of copper placed at its end, or by any of the other, means utilized for accomplishing a slow action of the relay when deenergized.

The common group of contacts 2 is that which is operated simultaneously with the operation of the switch for connecting purposes, and serves to disconnect the drop 18 from the trunk line 8 and to insert in one side of the trunk line the relay 1 The operators set is shown at '20 and may be of any typesuitable for employment in common battery working. The operators set has-associated with it the battery feed coil 19, the circuits of which are controlled through the hook switch 20 This battery feed coil 19 serves to supply current from the battery for the operators transmitter and that of any of the local stations with which the circuit of her set may have been connected.

Having described the apparatus employed and its general arrangement, I will now describe the operation and the circuits involved in a connection between two local stations.

I will assume that the station 5 wishes to communicate with station 7 The subscriber at station 5 removes his telephone receiver from the hook, causing the display of signal 9. The operator on observing the signal will move the switch 2 in proper position to actuate the springs of group 5 The operation of switch-2 in this position will automatically restore the signal 9 and connect the circuit of the operators telephone set to that'of station 5. The operator, upon learning that station 5 wishes connection with station 7 will disconnect switch 2 from the group of springs 5 either manually or by adjusted the switch 2 to the movlng her hook switch, which serves to break the circuit of the holding coil 31 of this switch and will then set the switch in proper position to actuate one of the selective groups of springs, as, for example 12 The switch 2, after being thus operated, will remain in an actuated position due to the fact that the subscriber has his receiver removed from the hook switch and the current through his station passes through the holding coil 31 of the switch 2. The operator will ring station 7 by means of the ringing key 16 and then adjust switch 1 in the proper position to actuate the selective group of springs 12*. This switch will remain in an actuated position due to the fact that the circuit of the holding coil 31 is connected through the common group of springs 2 and the selective group of springs 12 to the connecting circuit 12 and thence to the line of station 5, the circuit of which is closed. The two stations will then be properly connected for conversation. When the subscriber at station 7 removes his telephone from the'ho'ok, he will receive battery current suitable for energizing his transmitter in a manner similar to that to be described for station 5.

The circuit by which the actuation of the calling signal 9 is produced is, as follows: from the ungrounded pole of the battery to and through the right hand winding of signal 9, thence to and through normally closed contacts of group 2 thence to and through normally closed contacts of group 5 normally closed contacts of key 14 to station 5, through the instrument of that station, returning to and through normally closed contacts of key 14, normally closed contacts of group 5 normally closed contacts of group 2 thence to the left hand winding of signal 9, returning to the grounded pole of the battery, thus establishing a circuit for operating signal 9.

The circuit established when the operator proper position to actuate the group of springs 5 is as follows: from the grounded pole of the battery to and through the right hand winding of coil 19, normally open contacts of grou J 5 thence to and through the subscribers station, returning to the other normally open contacts of group 5 thence to the left hand winding of coil 19, contacts of hook switch 20 returning to the ungrounded pole of the battery.

The operators circuit is connected to that of switch 2, as follows: from a point between the right hand winding of coil 19 and group of contacts 5 to and through normally closed contacts of key 17 to and through the operators transmitter and induction coil, returning through normally closed contacts of key 17 to a point between the left hand winding of coil 19 and group of contacts 5 The switch 2 is held in an operated position, as follows: from the ungrounded pole of the battery to and through the right hand winding of coil 31, to and through the right hand set of normally open contacts of relay 1, resistance associated with relay 1, left hand set of normally open contacts of relay 1*, relay 1 being in an operated position, left hand winding of coil 31, returning to the grounded pole of the battery. The relay 1 was operated simultaneously with switch 2, as follows: from the ungrounded pole of the battery, normally open contacts of hook switch 20 normally open contacts of group 5 winding of relay 1 to ground.

The removal of the switch from the group of contacts 5 to group 12 has connected the line of station 5 to the connecting line 12 at 12 has disconnected the operators set at 5 and by breaking the normally open contact at 5 has caused relay 1 to become deenergized. The circuit for the battery supply for the transmitter of station 5 is now as follows: from the ungrounded pole of the battery to and through the right hand winding of coil 31, the right hand normally closed contacts of relay 1 normally open contacts of group 2 normally closed contacts of group 5 normally closed contacts of key 11 to and through the instrument of station 5, returning to and through normally closed contacts of key 14, normally closed contacts of group 5 normally open contacts of group 2 the left hand normally closed contacts of relay 1 left hand winding of coil 31, returning to the grounded pole of the battery.

The adjustment of switch 1 to actuate the group of springs 12 has established a circuit for supplying current to the local station 7, which is similar to that previously traced for station 5, and has also connected the local line 7 to connecting line 12 at 12 in a similar manner that station 5 was connected to connecting line 12. These circuits are, therefore, proper for sup )lying talking current to stations 5 and i, for holding the switches 2 and 4 in an operated position, and for connecting the circuits of these two stations together for conversation. When the subscribers at stations 5 and 7 hang their receivers on the hooks, the coils 31 and 31 will cease to be energized and therefore the switches will returnto their normal positions.

I will now describe the operation and circuits involved in a connection between a trunk line and one of the local lines.

I will assume that a subscriber connected through the public exchange to the trunk line 8 desires to communicate with the subscriber at local line 6. The signal 18 of the trunk line 8 is operated by the operator at the central exchange. The local exchange operator moves key 17 to the listening position and is informed that connection is desired with local station 6. She then moves key 17 to the holding position, which places the holding coil across the line 8. After determining by inspection that line 6 is free, she rings that line by means of key 15 and then, when the subscriber at that station answers, adjusts switch 3 in the proper position to actuate one of the groups of selective springs, as, for example, 13 and also adjusts and operates switch 1 to actuate the group of springs 13 The line of station 6 has now been extended to switch 1, and thence through switch 1 to the trunk line 8. The operation of switch 1, as has previously been described, restored the holding key to its normal position and thereby disconnected the holding coil from the line.

The circuits established with the switches 1 and 4 in their depressed positions are as follows: from the right hand terminal of trunk line 8 to normally closed contacts of group 2 normally open contacts of group 13 connecting line 13,. normally open contacts of group 13 normally closed contacts of ringing key 15, thence to and through the station of line 6, returning to and through normally closed contacts of ringing key 15, normally open contacts of group 18 connecting line 13, normally open contacts of group 18 normally open contacts of group 2 winding of relay 1 thence to the left hand terminal of exchange line 8. It will be noted that there is included in this circuit the winding of relay 1 The normally open.

the battery, thus operating relay 1 which, when operated, connects the windings of the holding coil 31 in series with resistance across the local battery. The circuit thus established is as follows: from the ungrounded pole of the battery to and through the right hand winding of coil 31 and right hand normally open contacts, resistance, and left hand normally open contacts of relay 1 thence to and through the left hand winding of coil 3-1 returning to the grounded pole of the battery. The circuits just described, therefore, are proper for maintaining the connection between the trunk line 8 and the local line 6.

At the end of conversation, when the subscriber hangs his receiver on the hook, the apparatus involved in the connection at the private branch exchange is restored to its normal condition. It will be remembered that the winding of relay 1 is included in one side of the circuit extending from trunk line 8 to the local line 6, and that the relay 1 when operated, serves to complete a circuit for the holding coil 31 of switch 1, and therefore serves as a means of retaining switch 1 in its operated position. It will also be remembered that the windings of the coil 81 were maintained in an energized con dition by a circuit which passed through the extreme right hand contacts of group 13 Therefore, when the subscriber at station 6 hangs up his receiver and allows relay 1 to return to its normal position, the holding coil 31 of switch- 1 will be d'eenergized, thus allowing this switch to return to its normal position, and by such return will break the circuit of the holding coil 31 thus allowing switch 3 also to return to its normal position. All apparatus at the branch exchange has now been restored to its normal position. The breaking of the circuit at the subscribers station will also cause the supervisory signal at the central exchange associated with the trunk line 8 to be displayed, indicating to the operator that the conversation is finished.

The relay 1 associated with switch 1, as has previously'been described, is of the slowacting type, the object of this being to provide a means whereby a subscriber at the private branch exchange, desiring a second connection, can obtain it without involving the operator at the branch exchange. We will assume that the subscriber at station 6, instead of having placed his receiver on the hook, moves the hook switch up and down rapidly, thus flashing the supervisory signal at the central office, and thereby signifying that he desires her attention on the line. A rapid movement of the hook switch will not permit the slow-acting relay 1 to return to normal, and consequently the subscriber may obtain a second connection without necessitating the re'stablishment of the connection between his line and the trunk line at the local exchange.

In the figure illustrating the circuit arrangement or" my invention, I have shown only one trunk line and three local lines; however, I do not wish to limit my invention in this respect, as it is obvious that the number of such lines may be increased without departing from the spirit of my invention.

While I have illustrated and described certain forms of my invention, it is understood that numerous changes may be made therein without departing from the spirit or narrowing the scope of my invention.

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:

1. In a telephone system, a plurality of lines, manually operated switches individual to said lines, said switches being adapted to a rotarymovement to select a connection and by a longitudinal movement to establish the connection, electromagnetic means associated with each switch for holding it in its connecting position, and means operated by the connected subscribers for causing said electromagnetic means to release said switch to disconnect said lines, substantially as described.

2. Ina telephone system, a plurality of lines, switches individual to said lines for connecting said lines together, means for manually rotating a member of each of said switches to select connection terminals, and means for longitudinally moving said member for establishing the connection with the terminals selected, electromagnetic means for locking said member in its connecting position, and means operated over the connected telephone lines for releasing said member from its connecting position, substantially as described.

3. In a telephone system, a plurality of lines, a common source of current for said lines, manually operated switches for connecting said lines together, groups of selective contacts for each cf said. switches whereby said switch may selectively extend the circuit of its line, and a group of contacts individual to each switch for operating to change the current supply from its normal path whenever a switch is operated, substantially as described.

4. In a telephone system, a plurality of lines, a line signal for each line, manually operated switches for connecting said lines together, groups of selective contacts for each of said switches whereby said switch may selectively extend the circuit of its line, and a group of contacts common to said selective groups on said switch adapted to cut oil said line signal whenever said switch is operated, substantially as described.

5. In a telephone system, a plurality of lines, a line signal for each line, a common source of current normally connected to each line through its individual line signal, groups of selective contacts for each of said switches whereby said switch may selectively extend the circuit of its line, and a group of contacts common to said selective groups on each switch adapted to cut off said line signal and to reestablish a connection from said common source for talking purposes, substantially as described.

6. In a telephone system, a plurality of lines, talking battery supply circuits normally disconnected from said lines, manually operated switches for connecting said lines together, groups of selective contacts for each of said switches whereby said switch may selectively extend the circuit of its line, and a group of contacts common to said selective groups on each switch, adapted to connect said talking battery supply circuit with said line when said switch is operated, substantially as described.

7. In a telephone system, a trunk line and a plurality of local lines, a manually operated switch for said trunk line adapted to extend said trunk line to any one of said local lines, a manually operated switch for each of said local lines adapted to selectively connect said local lines with each other, and electromagnetic means associated with each of said manually operated switches for holding said switches in their connecting positions, and means operated over the lines for causing said switches to disconnect said lines, substantially as described.

8. In a telephone system, a trunk line, a plurality of local lines, link circuits for interconnecting said lines, a manually operated switch for said trunk line adapted to selectively connect the trunk to any one of said link circuits, a manually operated switch for each of said local lines, each adapted to selectively connect its local line with one of said links, electromagnetic means associated with each of said manually operated switches for holding said switches in their connecting positions, and means operated over the lines for causing said switches to disconnect said lines, substantially as described.

9. In a telephone system, a trunk line, a plurality of local lines, link circuits for interconnecting said lines, a manually operated switch for said trunk line having a group of selective contacts for each link circuit, a manually operated switch for each local line, each adapted to selectively connect its local line with one of said link circuits, and electromagnetic means associated with each of said manually operated switches for holding said switches in their connecting positions, and means operated over the lines for causing said switches to disconnect said lines, substantially as described.

10. In a telephone system, a switching device consisting of a shaft capable of rotary and longitudinal movements, a contact actuating member carried by said shaft and partaking of its movements, groups of springs lying adjacent to the circular path of said contact actuating member, means for rotating said shaft to select one of said groups, means for moving said shaft longitudinally to cause said contact actuating member to engage the springs of said group, a line signal common to said switching device, and

a group of springs common to said other groups, and means for restoring said line signal and actuating said common group of 15 springs upon the longitudinal movement of said shaft, substantially as described.

WILLIAM AITKEN.

Witnesses:

R. W. MoUL'roN, -WM. MURPHY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

